Poll: Obama Leading Among Registered Voters

Slate reports that while two new polls out on Friday show President Obama leading challenger Mitt Romney, the extent of the president's lead differs depending on which Americans the pollsters believe are "likely voters."

The Reuters/Ipsos survey, which was taken during a four-day stretch ending yesterday, has Obama up by 7 points among what it classifies as likely voters, 48 percent to 41. That number falls one tick to 6 points, 45 percent to 39, among registered voters. Obama's lead in the Reuters survey has been steadily growing since he pulled out to a two-point lead (46-44) the day after the DNC wrapped up last week.

A new survey from the New York Times and CBS News, meanwhile, offers a more complicated picture. Among registered voters nationwide, Obama leads his rival by 8 points, 51 percent to 43. But among the smaller "likely voter" subset (as defined by NYT and CBS), the president's lead falls to 3 points over Romney, a gap that is within the survey's margin of error.

Slate explains that it won't be clear exactly how "likely voters" are defined until Friday evening, when the full polls are released. But the results drive home something we already know: Approval ratings and other measures matter only to the extent that people who prefer one candidate over another actually bring those preferences to the polls and cast a ballot.